Enough math. Check out celtx (pronounced kelt-ix), an open source application that at its core is a solid screewriting tool, but it seeks to become an all-encompasing production tool.
Word to that. The best part is, they want to hear from users about what features to add.
The sRGB luminance curve is designed to be an approximation of a gamma 2.2 curve, but with a straightline portion near zero to avoid rounding errors in conversions.
Spitzak has the sRGB to linear conversion right:
x < .04045 ? x/12.92 : pow((x+.055)/1.055, 2.4)
And here’s its inverse:
x < .0031308 ? x*12.92 : (1.055*pow(x,1/2.4)) -0.055
The question mark is an if/then. If the conditional before it is true, do what’s before the colon. If false, do what’s after.
By far the best thing about all this linear color workflow stuff is that people can easily use one term to mean completely opposite things. For instance, we say that an image with a gamma of 2.2 looks right on a monitor of gamma 2.2, but in truth one of those is really the opposite of the other so that they can cancel out.*
He calls is darker card, the one that has not been corrected for display, “gamma encoded,” and calls the one that looks right to our eye “linear.” This terminology disagrees with mine, and with that of the inimitable Bill Spitzak. I like to use linear to describe linear light intensities, whereas Throb tends to use it to describe perceptual linearity.
But a perceptually linear image is indeed gamma-encoded, so I still think Throb’s page is a little confusing. I’m guessing he’s saying that the dark image you see is effectively gamma-encoded by the display device?
He and I and others actually had a conversation earlier this year on the Highend2D Shake mailing list about how corn-fusing all this stuff is. It boils down to the difference of describing the data in the file vs. the light that hits your eye. Perceptually linear = gamma encoded file. Perceptually dark = linear data.
It's always dangerous when some random website, mine included, starts claiming to be authoritative on matters of color, so I've always been carefull to be consistent with my terminology, label it as mine and not necessarily everyone’s, and declare my assumptions. Looks like Throb has a similar policy.
* And for that, I do apologize.